Last year I was given access to the financial balance sheet of an East European gold farm, selling on WoW, which allows an insight into income, expenditure and profitability – as well as sales channels.
I’ve posted the details at: http://ict4dblog.wordpress.com/2011/03/30/the-financial-life-and-death-of-an-east-european-gold-farm/
However, the postscript is that the continuing devaluation of WoW gold has led to at least a temporary shut-down of the operation. There is also a hint that only through botting can gold farming be viable.